Molding apparatus



March 11, 1941. L. H. PECK 2,234,604

HOLDING APPARATUS Filed June 3, 1937 5 Sheets-Sheet 1 INVENTOR LEE H.PECK fi BY March 11, 1941. L. H. PECK 2,234,604

HOLDING APPARATUS Filed June 3, 1937 5 s s 2 FIG. 3'

i 7 v I 27/ 37 1 I I as I i INVENTOR LEE H. PECK ATTONYS March 11, 1941.L P v 2,234,604

1101mm APPARATUS Filed e 1957 5 Sheets-Sheet s OUTER DIE STARTS INPRESSURE STARTS INVENTOR 'LEE H. PECK 1. H. PECK March 11, 1941,

HOLDING Arnanus Filed June 3, 19:57

5 Sheets-Shee t 4 I INVENTOR LEE H. PE CK at k H. PECK HOLDING APPARATUSFiled June 3, 1937 March 11, 1941.

5 Sheets-Sheet 5 FIG.

FIG. l5

R K m m If E m P m V; N H Y L 1 .r A F. L Y B Patented Mar. 11, 1941UNITED STATES PATENT OFFICE MOLDING APPARATUS Lee H. Peck, ChagrinFalls, Ohio, assignor to Porcelain Products, Inc., Findlay, Ohio, acorporation of Delaware Application June 3, 1937, Serial No. 146,134 8Claims. (01. 25-78).

This invention relates to improvements in apparatus for molding articlesby the compression of loose material. My invention is particularlyadapted for the production of porcelain insulators and like articleswhich are formed by compressing suitable mixtures of clay, flint,whiting and similar materials in a mold.

My invention provides novel apparatus in which a recessed mold iscarried by a rotating turret, the mold being subjected duringturretrotation to a loading or filling operation, a compressing operation andan ejecting operation. Various features of my invention are directed tonovel apparatus for loading the molds and for producing the compressionof the loose material to form a molded article, and novel apparatus forejecting or discharging the article after it is molded.

My invention provides novel apparatus for cleaning and preparing'eachmold before it is filled, for sizing the loose material'before it entersthe molds, for insuring that each mold receives an exactly measuredamount of the loose material, for providing the same compression for thematerial in'each loaded mold, and for giving each piece the sametreatment during ejection from the mold so as to produce uniform moldedarticles.

Among other novel features of my invention are the provision ofapparatus whereby the molded article is formed in a recessed mold and isheld under compression while being removed from the mold to preventcracks in the article.

Another feature of my invention is the provision of novel apparatus forfreeing the molded article from the molding machine at the close of theejecting portion of the cycle.

My novel apparatus is arranged with carefully designed clearancesbetweenthe compression dies and the walls of the mold recess so as to permitair to escape from the mold when the loose material is compressed, thusavoiding both the formation of fins of excess material at these pointsand at thesame time avoiding air pockets in the molded articles. Themold liner and the compression die surfaces are so constructed that,upon wear increasing the clearance between them, they are quickly andcheaply restored to original condition.

My invention also comprises novel arrangements for cleaning and sprayingthe molds and various details of structure pointed out in'thespecification and disclosed in the drawings and the essential featuresof which will be summarized in the claims.

In the drawingsj I Fig. .1 is an end view of the machine taken at theleft of Fig. 2, parts of the turret being broken away to show theprogressive steps in compressing'a molded article; I 1 along Fig. .2 is,a central longitudinal section the line 2.2 of Fig. l; a

Fig. 3 is a detailed perspective view of the part 33a of Fig. 2; 1 Fig.4 is a partial vertical sectional view through the innerdiecontrollingcam plate 21 superimposed on an elevation of theouter die controllingcam plate 35 so as to form a diagram illustrating the relative movementsof inner and outer dies;

Fig. 5 is an enlarged and distorted view of a portion of an inner-dieengagingthe compressed material and illustrating the clearance betweenthe die and mold liner; a

Fig. 6 is a detail sectional view along the line 6- 6 of Fig. 8 showingthe article ejecting mechanism at the bottom of the turret; Fig. '7 is adetail sectional view along the lines l--'l of Figs. 1 and 8; f

Fig. 8 is a detail sectional view along the line 88 of Fig.6; ;j 7

-Fig. 9 is a fragmental sectional view along the'line 9-9 of Fig. 1; l V1 Fig. 10 is a fragmental sectional view showing a modified mounting forthe 'outer'die; Fig. 11 is aperspectiveview of an article adapted to bemolded by the machine;

Fig. 12 is a wiring'diagram of mechanism for controlling the level ofmaterial in the feed trough;

Fig. 13 is a side elevation of the machine with drive and materialsupply apparatus;

Fig. 14 is adetail sectionaljview of a port-ion of the materialsupplyapparatus; while; I

- Fig. 15 is atop plan view of an end of the feed trough. I have shownmy invention as applied to a machine for producing porcelain insulators:of the general character illustrated in Fig. 11 hav. ing a generallycylindrical form with a cored hole in the center for receiving a nail orother securing member. This particular type of insulator has a recessedbottom and wire receiving grooves in the top asshown. It will beunderstood, however/chat my invention is applicable to the production ofothertypes of molded-article's. Certain; features of my invention areapplicable to apparatus comprising a single moldor a small number ofmolds, but to increase the efliciency and production of my apparatus Ishow a number of molds, for instance ten, carried by a rotating turret,the succession of operations being carried out on each mold as it passesthrough a certain portion of its path of travel. It will be obvious thatthe number of molds may be arranged to suit individual conditions.

In the present embodiment a turret I0 is mounted on a substantiallyhorizontal shaft H journalled in the frame l2 for rotation in a verticalplane. While the rotation of this turret may be provided for in a numberof different ways, I have illustrated a continuously rotated turretdriven by a motor l3 mounted upon a suitable base and acting through avariable speed drive which is belt connected to reduction gearing IS.The turret here illustrated is adapted to be run at the speed of 20 R.P. M. or thereabouts.

The turret is provided with a plurality of recessed molds l6, in thepresent instance ten, having openings I! at the periphery of the turret.In the present instance themolds open toward the outer periphery of theturret.- The mold recesses here shown are formed in the turret properand are provided with mold linings l8, thus giving accurate diameter tothe mold and providing for replacement of the linings when worn. To thisend the lining is carried by a sleeve l8a positioned in the turret byset screw l8b. Opposite the opening of each mold and forming .the bottomwall thereof is an inner die I9 which carries rigid with it a radiallyinwardly extending sleeve 20 adapted to slide upon a pin 2| which isrigidly fixed in the hub of the turret. The pin 2! also carries the corepin 22 for forming the central opening in the porcelain insulator, thispin being fastened in place in any suitable manner as by the fastening23 shown. Rigidly secured .to the sleeve is the block 24 which carriesthe cam follower 25 for coaction with a suitable cam 26 for controllingthe movement of the inner dies. The block 24 has a lug 24a which entersa suitable radial slot in turret ill to guide the movement of sleeve 20and die Hi. In the present embodiment the cam is a groove formed inplate 21 secured in a stationary manner to the frame on the outer faceof the turret. The followers 25, one for each inner die, compriserollers which travel in the groove of the cam. As will be laterexplained the formation of this cam is such that the inner die forms astationary bottom wall for the mold from the point where the mold isfilled at the top of its path and for its travel through substantially105 during which time the loose material in the mold is compressed.Thereafter the cam causes outward movement of the inner die for ejectingthe molded article.

Referring to Figs. 1 and 2, the sleeve 20 extends radially inwardlybeyond the block 24 so that it is the end of the sleeve which engagesthe shoulder am on pin 2| during the travel of the inner die controllingearn from the point F in Fig. 4 to the point C. In other words, duringthe time that compression occurs in the mold chamber, the cam rollers 25clear the cam track 26 by a and the reaction to the compressingoperationis all absorbed between sleeve 20 and the shoulder 2| a.

A series of outer dies 28 is provided, one for each mold, these diesbeing adapted to enter the openings in the recessed molds and tocompress the loose materlal therein. These outer dies are preferablyreciprocably mounted in the turret, the dies having stems 29 enteringguiding openings 30 in the turret for this purpose.-

Each die carries a head portion 3| having faces 3|a which engage snuglyin a guiding slot 32 formed radially in the turret and bevelled surfaces32a on the turret insure centering of the outer die in the mold openingbefore compression starts. The faces 3|a coast with slot 32 in absorbingany side thrust developed in the compression operation and holding theouter dies properly indexed at all times with reference to the moldrecess. Each of these outer dies carr-ies rigidly secured thereto by apin or shaft 33a a follower roller 33 adapted to engage in the groove 34of a cam plate 35 secured to the frame on the inner face of the turret.A portion 33b of roller shaft 330. (Fig. 3) engages a slot 36 in theturret and helps guide the die.

The arrangement between this cam plate 35 and the outer dies is suchthat the dies are in fully withdrawn position when at the top of theirpath where the molds are loaded with loose material. As the mold rotatesfrom this position, each die is rapidly moved inwardly until it engagesthe material in the mold at substantially the point -A (Fig. 4). Duringthe next portion of mold travel the outer die is moved inwardly toprovide very heavy pressure compressing the loose material in the'moldrecess to substantially half of itsoriglnal volume. This action issubstantially completed at the point B and this pressure is held for anadditional 10 until the point C is reached.

From the point C as the mold moves downwardlyboth inner and outer diesmove outwardly carrying the molded article out of the mold recess untilat the point D the outer die is rapidly moved outwardly to'its outermostposition leaving the molded article unsupported. From the point D to thepoint E the inner die continues to move outwardly and at the point E themolded article is finally released from the turret and drops under theinfluence of gravity a very short distance onto one of the rotatabledisks 3T carried by the conveyor chain 38 which carries the moldedarticles to the next processing step, which in the present instance ispassage through a drying kiln. Rotating vanes 31a steady each piece asit drops to the conveyor.

Preferably a hardened steel block 39 is provided forming the followerengaging surface of the outer die controlling cam between points A and Cwhere the greatest compression is developed. This may amount to as muchas 2500 pounds per square inch in the type of machine described.

I find that in removing the molded article from the mold recess the:article is likely to develop cracks when the outer die is withdrawn,either because the molded article sticks to the outer die or because avacuum is formed in the cylindrical portion of the mold recess as theouter die' is withdrawn, or possibly due to acombination of i To avoidthe formation of such both of these. cracks I prefer to hold the moldedarticle under compression while moving it out of the mold recess, atleast during that portion of the ejection period when the molded articleis first started outwardly of the recess. To this end I provide abacking block 40 for that portion of the outer die controlling camgroove between the points C and D. This block is preferably of hardenedsteel of the form shown, slidably mounted in a portion of the turret andyieldingly held in the position indicated in full lines in Fig. 4 by thesprings 4| shown. The free space outwardly of the block permits movementof the block'outward as indicated in broken lines in Fig. 4. As shown inFig. 4 a hardened steel pin 51 carried by the cam plate rests .betweenthe outer end of block 40 and the cam surface behind it so as to give atilting movement of block 40 about its outer edge. The formation of thecam surface 40a, of this block is such that as the mold passes the pointC and the inner die commences to move outwardly (controlled by its cam)the cam follower of the outer die is constrained to move slightlyinwardly if the block lies in its full line position of Fig. 4. Itresults from this construction that as the parts pass the point C theinner die presses on the bottom of the molded article but the outer dieconstrained by the cam portion 40a exertsthe pressure of the springs 41against the outer surface of the molded article so that it is held undercompression until the point D1 is reached and from this point to thepoint D the cam portion 40a is so formed that this yielding pressure isgradually reduced. By adjustment of the tension of springs 4| thepressure on the molded articles during removal from the mold is variedand this exerts a great effect upon the surface of the finished article.During the travel from C to D both inner and outer dies are movingoutwardly so that the molded article is moved through a major portion ofits ejecting phase by the'time the point D is reached. At this point theouter die is rapidly moved outwardly as previously described torelieveall pressure on the molded article so as not to bulge or distort it. Theinner die continues to' push the piece outwardly until it reaches thebottommost point in its path of travel.

' Special apparatus is provided for finally freeing the molded articlefrom the turret apparatus at the point of ejectment. This as best seenin Fig. 4 comprises a plunger 42 having an inclined face 42a adapted toengage the roller followers 25 controlling the movement of the innerdies l9. This plunger is mounted for reciprocation in a dovetailedrecess in the cam and urged outwardly by the spring 43. The inclinedface of the plunger normally lies in the path of the upper portion ofthe cam follower roller as it reaches the bottom of its path of travel.At the point 44 the cam groove 26 is cut away sharply, thus removing allsupport for the cam follower roller at this point. As best seen in Figs.6 and 8, the pin 250. which supports cam follower roller 25 has a roundhead 25b which is 3 2 less in diameter than the roller 25. The head ofthis pin is flattened on two sides as at 250 at distances from thecenter of the pm. A hardened steel block 45 having a bevelled entranceend 45a is inserted at the back of the cam track 26. As the roller 25travels along the surface 26 the shoulder 250 on the pin has clearancefrom the block 45. As the roller 25 drops off the shoulder 44 thesurfaces 250 and 45 engage. Meanwhile as the turret continues to rotate,the cam follower roller urges the plunger upwardly compressing thespring 43, and as the shoulder 250 on the follower pin clears thestationary shoulder 45, the spring pressed plunger kicks the inner dieoutwardly a short distance, thus freeing the molded article from. theinner die and permitting it to drop the short distance to the conveyor.

Means is provided for cleaning the dies on the return travel indicatedby the left half'of Figs. 1 and 4. For instance, a blast of air might beused and the rotary brush 41, drivenby motor 41a, is provided to cleanthe face of the inner die while of the outer die at the same time;

Means is provided also for coating the interior of the mold recess andthe faces ofthe outer and inner dies preparatory to anothervm'olding'operation. A suitable material for this purpose is a mixture ofparaffine oils and kerosene. However, there are other materials whichmight be used at thispoint. In the apparatus shown, a. reservoir 48 ofoil is provided underfair pressure supplied from the pressure conduit 49and on is directed into the mold recess and against the face of theinner die by conduit 50 and'against the face of the outer .die byconduit 5!. This same oil 'under pressure may be conducted by suitableconduits 52 to other points on the apparatus needing lubrication.Control buttons- 68'on the face of the turret operate a control valve 69as shown in Fig. 9 so as to control the discharge of oil vapor throughthe outlets 50 and 5|.

A similar valve operated by these same buttons 68 may be utilized torelease a blast of air at each die 28 and die guiding stem '29 after themold is filled and before the outer die begins to compress the material.This insures 'a'clean die stem 29' where it enters the turret on itsinward stroke.

The outer die remains in its outermost position as shown from-the pointEand throughout about 1809' of travel un'tilit again passes its uppermostposition except for ra-slight dip near the point E where the outer diepasses beneath the conveyer. The inner die after it passes therotarybrush is withdrawn by it's controlling cam'to its innermost position atthe point F and remains in this position until it again passes the pointC. Referring to Figs. 1 and 4, a leaf spring 10 is fastened to the upperedge of cam plate2'l in position to engage the'rollers 25 as they passthat point and insure that sleeve 20 is in engagement with the shoulder2|.a, thus insuring the lowest position of die l9 at the'time the moldis filled and insuring a uniform filling of the mold.

Preferably means is provided for automatically fillin'geach mold recessWithout stopping turret rotation. To this end closely engaging the upperarcuate surface of'the turret is a feed trough 53 or loose materialreservoir which-may be formed of sheet metal and supported by the arms54 from the hub of the turret. Material from the hopper 55 drops ontothe shaker feeder 56 and thence passes. through the chute 51tothe feedtrough or reservoir. If necessaryor d-esirable a screen 58 'may beprovided above the shaker feeder to insure proper sizing. of materialbefore passing into the shaker feeder. Thetailings from this screen maybe led away by means of a tailing chute 59; The shaker feeder is'of awell known type operated 'by a solenoid coil 50 as illustrated butother. suitable feedingmeans might be provided. As the turret movesinthe direction of the arrow I provide within the reservoir a V-' shapedscraper member SI for folding'the'loose material from each'side inwardlyand for scraping the top of the mold-recess as it passes out of thefilling trough.

I have provided interlock'means for controlling the feeding apparatus inaccordance with the it is still in its extended position, andthe' face;

level of the material in the feed trough. "One of the purposes ofthisinterlock means is to prevent the feed trough running over. Anotherpurpose of the interlockmeansis to maintain a substantially constantlevel of the loose material in the feed trough. The density of themolded pieces varies with the level of the material in the "trough 53.Therefore uniform density" is insured by maintaining a constant level ata predetermined height. Also the density may be varied by a variation ofthe height of material in the feed trough. Various mechanisms may beprovided for this purpose but the preferred form is the one illustratedherewith which does not disturb the loose material in the trough to anyappreciable degree. I find that disturbance of material in the troughresults in a segregation of the larger particles which is adisadvantage.

As shown in Figs. 1, 2 and 12, in the feed trough 53 I place a pair ofcondenser plates 1| which are arranged in circuit with a vacuum tube 12so as to interrupt the operation of the shaker feeder 56 in accordancewith the level of material in the trough 53. The shaker feeder isoperated by a solenoid coil 80 acting on an armature secured to thefeeder and supplied with current from a source 13 controlled by button14 and including a variable resistance controlled at 15 so as to varythe shaking actionv of the solenoid 60. The supply circuit for solenoid88 as shown in Fig. 12 includes lines 16 and 11 connected to two sidesof the source of electrical supply and having an interrupting switch 18normally held closed as by a spring 19 and adapted to be opened uponenergization of relay G0. The control circuit by which the level ofmaterial in trough 53 affects switch 18 is clearly shown in Fig. 12. Theprimary 8| of a transformer is connected to the electrical source andthe secondary is shown at 82 with a core 83. The relay 80 is connectedby line 85 with the transformer secondary and by line 88 with the anodeof tube 12. The cathode of the tube is connected by line 81 with thesecondary of the transformer 82. The grid of the tube 12 is connected byline 88, variable condenser 89 and line 90 with line 81. The condenserII is connected by lines 9| and 92 with lines 88 and 86 respectively.The tube shield is connected through resistance 93 with line 86. Thevariable condenser 89 is provided for tuning the circuit so that underthe normal selected conditions relay 80 will have no current flow,switch 18 will be closed and the solenoid 60 will operate.

This condition may be selected so that the material in trough 53 isbelow the plates II or at some predetermined position on those plates.With the above described circuit and material being fed through theshaker feeder, it is obvious that the feeder will normally operate untilthe loose material rises to such a point on plates H that thecapacitance of the circuit is changed, causing a flow through tube 12and the energization of relay 80 thus opening the switch 18 and causingthe shaker feeder to stop until the loose material in trough 53 hassubsided to its predetermined normal level, at which time switch 18 willagain close and the shaker feeder will operate.

While it will :be understood from the drawings that the control cams forthe inner and outer dies are on opposite sides of the rotating turret inthis particular embodiment, there is no reason why they could not bothbe placed upon one side of the turret and for simplicity of illustratingtheir interaction the diagram of Fig. 4 shows the two cam grooves onewithin the other.

The cam plate 35 for the outer dies is cut away at the top as shown at65 permitting the easy removal of the dies at this point. The cam plate21 for the inner dies is cut away at 66 as shown so that the dies areeasily removed at this point, no outer controlling cam surface beingnecessary at this place.

Referring to Fig. 5, exit of air from the mold cavities is only by wayof clearance between the dies I9 and 28 and the mold wall [8. Thequantity of air trapped in the mold cavity will be less if the fillingmaterial is properly graded and screened and free of large lumps, andwill be less if the mold cavity is entirely filled before compressionstarts. Vice versa, the amount of trapped air will be greater if thematerial is not carefully graded or contains large lumps, or if the moldcavity is not well filled.

Unless the trapped air can escape from the mold cavity,'tlie surface ofthe formed articles will be rough and uneven due'to the formation of airbubbles at the confining surfaces and the density of the formed pieceswill vary because of the entrapment of air pockets in the finishedpiece.

To insure suflicient clearance for the discharge of entrapped air, Ifind it desirable to provide a clearance at point G between dies I9 and28 and the mold liner I 8 of approximately .0025 of an inch all roundwhen the dies are new. This is for forming the article shown, which isof approximately l fi diameter and may vary, of course, under othercircumstances and with other articles or other molding substances. When,during the use of the machine, this clearance approaches .006 of aninch, the clay material is likely to enter this clearance space as shownat H, causing improperly formed articles and undesirable wear of the dieand mold walls. Therefore I prefer to renew the parts when the wearreaches this point.

I find very satisfactory working conditions are provided when the diesl9 and 28 are chromium plated as at l9a and the mold liner I8 is ofhardened steel. When the dies become worn, it is only necessary to stripthe remainder of the chromium plating from them, replate them withchromium and grind the dies to size.

Referring to Fig. 10, another method of insuring a yielding pressureagainst the molded articles while they are being stripped from the moldis to insert a rubber gasket (or a spring mounting) at 92' between thedie 28 and its supporting member 3|. A pin 93 supports the die 28 whilepermitting compression of the rubber.

The gasket 92 is fully compressed by the time point B or C is reached.Then the outer die is moved outwardly more rapidly than the inner dieand the compression of the rubber relieved at any rate desired until thepoint D is reached, when it is zero. In such a device the block 48 isnot needed.

Pieces of satisfactory surface formation and of uniform density areobtained only by proper preparation of the molds, by a careful controlof clay composition, clay moisture, clay sizing,

- uniform filling of the mold cavity, uniform compression of the loosematerial, adjustment of the compression during ejection, and care of theclearance G. My improved machine places all of these under automaticcontrol with adjustability at the various points as specified so thatuniform articles may be produced.

What I claim is:

1. In apparatus for molding articles by compressing loose material, aplurality of movable molds open at the top, a feed trough for loosematerial beneath which said molds pass, whereby said molds are filled bysaid material falling by gravity into said molds, and means formaintaining said loose material at substantially a -constant level insaid trough over a filling mold.

2. In apparatus for molding articles by compressing loose material, aplurality of molds in a mold carrier, dies adapted to compress thematerial in said molds, means for moving one of said dies to ejectcompressed material from its associated mold, and means for tapping saidone die after it has made a portion of its, ejecting movement, torelease the compressed material.

3. In apparatus for molding articles by compressing loose material, aplurality of molds in a mold carrier, dies adapted to compress materialin said molds, said carrier being arranged to move said molds to a pointof ejectment, one of said dies being an ejecting die for removingcompressed material from the molds, a springpressed plunger arranged tocoact with each ejecting die at said ejecting point, a cam track forguiding said ejecting die to load said plunger spring as the ejectingdie approaches the ejecting point, and said cam track being arranged tosuddenly release said die to the action of said plunger.

4. In molding apparatus of the class described, a mold open at oppositeends, an ejecting die adapted to close one end of said mold, acompressing die adapted to enter the other end of said mold, meansincluding a cam track having a rigidly held compressing portion formoving said compressing die in a direction to compress loose material insaid mold against said other die, means for moving both of said diessimultaneously at substantially the same speed in an opposite directionto eject said compressed material from said mold, and said last namedmeans including said cam track controlling said compressing die, saidtrack having a yielding portion located beyond the compressing portionthereof and yieldingly holding said compressing die during at least thefirst portion] of said movement in said opposite direction.

5. The combination of claim 4 in which said last named cam track portionis a separate elongated member pivoted at its end nearer the point ofejection of said compressed material.

6. The combination of claim 4 wherein said yielding track portion isheld in position by springs, and including means for adjusting thetension on said springs.

7. In apparatus for molding articles by compressing loose material, arotatable turret, there being a plurality of mold recesses radiallypositioned in said turret and open at their inner and outer ends, diesadapted to enter said inner and outer ends respectively, means formoving said outer die into said mold during a portion of the turretrotating cycle for compressing loose material in said mold, a stationarycam for controlling said inner die, a follower on said inner die forengagement with said cam, support means for said inner die rigid withsaid turret and in dependent of said cam and follower, said supportmeans being so arranged as to be efl'ective during said materialcompressing portion of the turret cycle, and said cam and follower beingarranged to move said inner die for ejecting the formed article from themold recess during another portion of the turret rotating cycle.

8. In apparatus for molding articles by compressing loose material, arotatable turret, a plurality of recessed molds carried by said turretand opening radially outwardly toward the periphery of said turret, aradially inner die forming the bottom of each mold, a radially outer diefor each mold carried by said turret and adapted to enter said opening,means for rotating said turret, means for causing during turret rotationinward movement of each outer die to compress material in the recess ofits associated mold then outward movement of said outer die to permitejectment of compressed material from said mold, a spring-pressed memberoperatively associated with each inner die and stressed in a directionto cause radially outward die movement as each mold approaches ejectingposition, and means for suddenly releasing said member as each moldreaches ejecting position.

LEE H.'PECK.

